An alternating current (AC) electronic monitoring system (EMS) was successfully used for the first time to record probing behavior of thrips. During electronic monitoring of Frankliniella occidentalis (Pergande) on leaves of broad bean, Vicia faba L., two types of patterns were recorded. One was of short duration and may represent shallow feeding from epidermal cells. The other was of long duration and may represent feeding from cells deeper in the leaf. The EMS was interfaced with a microcomputer. The importance of this approach to increasing the number of insects monitored simultaneously and to automation of recording analysis are discussed.